The formula H2O is also the molecular formula of water. For non-molecular substances such as table salt, we represent the composition with an empirical formula. Sodium chloride is represented by NaCl, meaning that sodium and chlorine ratio in sodium chloride is 1 to 1. Again, the subscript 1 is omitted.
By Phil Myers. The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity.Segmentation is also called metamerism.y Phil Myers. The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity.
Flatworms. Flat worms are soft-bodied invertebrate animals from the platyhelminthes phylum. They take in oxygen but have no formal respiratory system. This is because they are very simple animals.They went through such small evolution that they never developed a complex respiratory system.lat worms are soft-bodied invertebrate animals from the platyhelminthes phylum. They take in oxygen but have no formal respiratory system.